1. Field of the Invention
The present invention relates generally to a heat source sensor and, more particularly, to a sensor unit for sensing a heat source near a marine vessel and, more particularly, to a sensor unit that is particularly configured to be mounted on the marine vessel in combination with another sensor unit to detect the heat source in a region behind the transom of the marine vessel.
2. Description of the Related Art
Those skilled in the art of sensing sources of heat are familiar with the use of infrared detectors and motion sensors to accomplish this purpose. In addition, those skilled artisans in the field of sensing heat emitting objects are aware of many different systems that are capable of determining the presence of a mammal, such as a human being, within the sensing area of an infrared sensor. Furthermore, those skilled in these fields are aware that most heat sensors operate on the concept of sensing a change in the location or intensity of a heat emitting object. As such, these sensors typically react to the movement of a heat emitting object into or out of the sensing region of the sensor.
U.S. Pat. No. 3,936,822, which issued to Hirschberg on Feb. 3, 1976, describes a method and apparatus for detecting weapon fire. Radiant and acoustic energy produced upon occurrence of the firing of a weapon and emanating from the muzzle thereof are detected at known, substantially fixed, distances therefrom. Directionally sensitive radiant and acoustic energy transducer means directed towards the muzzle to receive the radiation and acoustic pressure waves therefrom may be located adjacent each other for convenience.
U.S. Pat. No. 3,958,118, which issued to Schwarz on May 18, 1976, describes an intrusion detection device. It includes an array of infrared detectors with associated means for selectively increasing the number of scanned zones which may be monitored by the same detector array, by providing an optical system with reflectors and/or lenses having a multiplicity of facets set at selected angles to direct primary impulses received from the portions of the entire scanned field sequentially to the detector array.
U.S. Pat. No. 4,982,176, which issued to Schwarz on Jan. 1, 1991, describes a solar powered lighting and alarm system activated by motion detection. Solar powered outdoor lighting and/or alarm systems are provided and include a light source or alarm, a passive infrared sensor in conjunction with a battery recharged via solar cells, and a control circuit coupled to the light source or alarm, the PIR (passive infrared) sensor, and the rechargeable battery.
U.S. Pat. No. 5,074,488, which issued to Colling on Dec. 24, 1991, describes an aircraft engine deactivation apparatus. The apparatus is intended for stopping an aircraft engine while the aircraft is on the ground. The apparatus is for safety purposes and is used to prevent a detected object from coming into contact with an engine driven propeller or a jet propulsion intake. A detector, preferably an infrared radiation sensor, detects an object or person within the selected distance and within a selected area about the engine. Upon detection, a mechanical engine deactivator, such as brake calipers engageable with the engine flywheel, or an electronic deactivator, such as an electronic switch operable to ground magnetos, shuts down the engine.
U.S. Pat. No. 5,283,427, which issued to Phillips et al. on Feb. 1, 1994, describes a night sight for a missile launcher comprising an image intensifier tube, a reticle, and an objective lens. The night sight has an objective lens with a field of view of at least 22 degrees. The output image of the objective lens is intensified by a variable gain light intensifier tube and the output of the intensifier is viewed through an eyepiece. A reticle pattern etched on a glass substrate and filled with titanium dioxide is illuminated by adjustable brightness LED's positioned at points on the periphery of the substrate.
U.S. Pat. No. 5,987,205, which issued to Moseley et al. on Nov. 16, 1999, describes an infrared energy transmissive member and radiation receiver. The infrared energy transmissive member is intended for conducting infrared energy from a first end of the infrared energy transmissive member to a second end disposed adjacent an infrared responsive circuit component of an infrared receiver, the member comprising a flexible hollow plastic tube.
U.S. Pat. No. 6,100,803, which issued to Chang on Aug. 8, 2000, describes an infrared illuminative warning detector. The detector includes a base seat formed with at least four perforations for two light shades and two detector heads to insert therein. A bulb is installed in each light shade. An infrared detector is disposed in each detector head for detecting alien article within a detection range and lighting up the bulb. Each light shade and detector head is disposed with at least one shifting mechanism for freely changing operating position.
U.S. Pat. No. 6,354,892, which issued to Staerzl on Mar. 12, 2002, discloses a safety device for a marine vessel. It provides an infrared sensor with a tube having a central cavity in order to define a viewing angle which is more narrow than the inherent viewing angle of the infrared sensor. The central cavity of the tube also defines a line of sight that can be directed toward a particular region near a marine vessel that is to be monitored for the presence of a heat generating object, such as a human being. An alarm circuit is responsive to signals from the infrared sensors and deactivates the marine propulsion system when a heat generating object is near the marine propulsion system.
U.S. Pat. No. 6,380,871, which issued to Kaplan on Apr. 30, 2002, describes a search for and method of searching for targets in a marine environment. An above-the-water system for and method of finding targets, both animate and inanimate, in a marine environment, especially by determining the distance and depth of targets at, above, or below the surface of, the water. An optical transmitter transmits infrared and ultraviolet light beams toward different zones of coverage on the water. An optical receiver equipped with a segmented detector separately detects return target reflections. An indicator, including range and depth indicators, provides information as to the distance to the target and, if it is below the water, its depth.
U.S. Pat. No. 6,450,845, which issued to Snyder et al. on Sep. 17, 2002, discloses a passive occupant sensing system for a watercraft. A tetherless occupant detector system uses an infrared sensor and a monitor circuit that provides a deactivation signal to an engine control unit or other control mechanisms in the event of an operator of the marine vessel leaving a preselected control position at its helm. The infrared sensor provides an output signal that is generally representative of the heat produced by an occupant within the control position of a marine vessel.
U.S. Pat. No. 6,676,460, which issued to Motsenbocker on Jan. 13, 2004, describes an electronic propeller guard. Electronic methods, devices and kits electronically protect swimmers, animals and other objects in water from propeller strikes, and alleviate propeller damage. Desirable embodiments include continuous ultrasonic sensing and detection by separate sensors to minimize reaction time for stopping internal combustion engine and electric motor driven propellers.
U.S. Pat. No. 6,693,561, which issued to Kaplan on Feb. 17, 2004, describes a system for and method of wide searching for targets in a marine environment. An above-the-water system for and method of finding targets, both animate and inanimate, in a marine environment, especially by determining the distance and depth of targets at, above or below the surface of, the water is disclosed. An optical transmitter transmits infrared and ultraviolet light beams toward different zones of coverage on the water.
U.S. Pat. No. 6,737,971, which issued to Knaak on May 18, 2004, describes an apparatus for detecting an object approaching a vessel and associated method. The apparatus includes a laser light curtain comprising at least one pulsed laser light beam extending radially from the ship toward a perimeter thereabout, the laser light curtain positioned spaced apart from and approximately parallel to an approach surface for detecting an object interrupting the light curtain.
U.S. Pat. No. 7,105,800, which issued to Staerzl on Sep. 12, 2006, discloses a detection system and method for a propeller driven marine vessel with a false triggering prevention capability. The detection system uses an infrared sensor to detect the presence of a human being or mammal in a target area near the propeller. A visible light detector is used to determine whether or not a signal received from the infrared sensor is caused by reflected sunlight and not the actual presence of a human being or mammal. By detecting visible light, false triggering of the system in response to infrared radiation received from sunlight can be significantly reduced. Embodiments of the system can monitor gear position and engine speed in combination with signals received from the infrared sensor and visible light sensors to determine an appropriate action to take in response to the presence of infrared radiation above a preselected threshold.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Although it is well known to those skilled in the art to use infrared detectors and alternative types of motion detectors to sense the presence of a heat emitting object, such as a mammal, within a detection zone, the appropriate use of this type of device in a marine environment is difficult because of the presence of many heat sources other than mammals. For example, sunlight reflected by the surface of the water can provide false triggering because of the rapidly varying magnitudes and directions of infrared light resulting therefrom. Additionally, heated cowls of outboard motors can provide a sufficiently intense infrared signal that a detector might incorrectly identify as a mammal in the region of the outboard motor. It would therefore be significantly beneficial if a detection system could be provided for sensing the presence of heat emitting objects within a preselected detection zone which is less sensitive to false triggering and easily adapted for use with a marine vessel.